Steel threads

[jhe888]

There have been a few discussions about stainless steels here over the last few days. This is a far more complicated topic than these discussions even hint at. I only know just enough about steel to know that I don't know much about it.

Hardness, toughness, stain resistance, and workability are qualities steel can have, and which various alloys have in differing degrees. There is no one best steel as it depends on the application, and you would even have disagreements about which steel is better in a particular application, as one alloy may be superior in one respect and inferior to another in a different quality. The stainless steels that make good watch cases would make terrible knives, and a steel that makes a good filet knife would not be very good for a chopping knife, for example.

There have been a lot of misconceptions shared in some of these threads, and misuse of terms. Some people seem to buy the marketing department's hype without really knowing what is going on.

Here is some actual information:

904L is very stain resistant and resistant to acids. Apparently it polishes up very nicely, welds well, and is workable. It is tough, which isn't the same as hardness. http://www.azom.com/article.aspx?ArticleID=1022

316L is similar, although probably not as resistant to acids. It also welds well, and is tough. We all have watches made from it, so we know it polishes nicely. http://www.azom.com/article.aspx?ArticleID=2382

Both make a fine watch which will not corrode under normal use, even if that use includes exposure to salt water. I bet Rolex could switch back to 316, and no end user of watches could tell the difference. 904 may have some advantages, but they seem slight in this application.

Here are some general pieces about stainless in general, which, at least, give a hint as to how complex the subject is.

http://www.asminternational.org/docu..._Chapter_1.pdf

http://www.azom.com/article.aspx?ArticleID=470

Here is the definition of terms that describe metals, so we can use them correctly:

http://www.tpub.com/air/1-18.htm